The use of thiol-based depilatory agents, such as thioglycolic acid, for removal of unwanted body and facial hair is well established in the art. These agents react by reducing hair's protein disulfide bonds to sulfhydryl anions, thereby allowing easy removal of the weakened hairs when washed or wiped away. However, in using thiols, it was discovered that certain conditions facilitated the effectiveness of this reaction. One such condition is high alkalinity to provide ionized reactants. Not only do the high pH's (approximately 12.0-12.5) result in ionized thiols, but they also result in increased penetration of a reactant. Thus, substances to provide further enhancement of penetration by active thiols were developed.
Further progress in the area of depilation resulted in the development of compounds which seem to expose more of the disulfide bonds to thiol agents. It is thought that these compounds decrease inter and intra chain bonding in hair keratin thereby, "accelerating" the rate of penetration and thus reaction by the thiols. Ureas, thioureas, and guanidines are thought to react as such accelerators, and in fact, the prior art discloses many of these nitrogen-based depilatory accelerators. Among such prior art references are U.S. Pat. No. 2,192,380, March 5, 1940 to David Walker Jayne, Jr.: U.S. Pat. No. 3,194,736, July 13, 1965 to Ernest Brown & John E. Logan; Belgian Pat. No. 765,987, May 5, 1970 to Investigations Scientifiques Pharmaceutiques; U.S. Pat. No. 3,981,681, Sept. 21, 1976 to Mario de la Guardia; U.S. Pat. No. 3,271,258, Sept. 6, 1966 to Charles Zviak and Jean Rouet; U.S. Pat. No. 4,177,260, Dec. 4, 1977 to Theodor Wajaroff; French Pat. No. 2,168,202, Jan. 20, 1972 to Fabres SA P.; U.S. Pat. No. 3,686,296, Aug. 22, 1972 to Harvey A. Yablonsky; and U.S. Pat. No. 3,728,356, Aug. 17, 1973 to Harvey A. Yablonsky.
In addition to the above-mentioned disclosures, biguanides have been chemically reacted with ethylene sulfide to form thiol depilatory derivatives, U.S. Pat. No. 2,453,333, Nov. 9, 1948 to Leonard P. Moore and Walter P. Ericks. In addition, U.S. Pat. No. 2,174,497, Sept. 26, 1939 to William H. Hill discloses a method of unhairing hides and skins by combining biguanide with an alkaline hydrolyzing agent. However, no thiol depilatory with biguanide as an accelerator is suggested by Hill.
The present invention provides not only more effective and faster removal of unwanted body and facial hair than urea accelerators, but the combination of biguanide with a thiol depilatory is safer for human usage in comparison to guanidine and thiourea accelerators.
It is an object of the present invention to provide safe and effective removal of unwanted body and facial hair. It is a further object to provide depilatory compositions containing biguanide and an active thiol depilatory agent. These and other objectives will become readily apparent from the detailed description which follows.
All percentages and ratios used herein are by weight unless otherwise specified.